The present invention relates to adaptive process control systems, such as adaptive vibration control systems. More particularly, one embodiment of the invention relates to a multiple-input multiple-output (MIMO) adaptive vibration control system controlled by an artificial neural system that generates, cancels, and/or reduces vibrations in a rigid or semi-rigid (e.g., solid) or fluid (gaseous or liquid) medium.
All processes that use or produce power are susceptible to vibration. Rotating machinery-driven equipment, such as turbine generators, cooling pumps, boiler feed water pumps, forced air draft fans, condenser pumps, conveyor belts, propulsion systems, lathes, mills, grinders, and other manufacturing machines are but a few of the more critical plant systems whose performance may be affected by vibration, either directly or indirectly. Vibration transmitted to neighboring structures or machines may also be detrimental. For example, operators of heavy machinery, trucks, aircraft, or spacecraft, to name but a few, may suffer fatigue due to excessive vibration and noise. Buildings and other rigid structures may suffer permanent damage due to vibrations caused by earthquake. Delicate instrumentation, laser and optical bench systems, automatic machinery, robots, cameras, etc., may also be adversely affected by vibration. Thus, there is a need in the art for vibration reduction systems that can be readily adapted to reduce or cancel undesired vibrations in any given type of system where undesirable vibrations may be present.
Vibrations may be transmitted through solid, liquid or gaseous mediums. Most of the examples presented above relate to vibrations in a solid medium, e.g., vibrations that appear in a metal housing, bearing, or other rigid or semi-rigid structures. It is to be emphasized, however, that vibrations may also be felt and transmitted in a fluid medium (gas or liquid), and that such vibrations may also be detrimental. For example, the vibrations associated with the motor of an underwater craft are readily transmitted through the water and make detection of the location of the craft by an unfriendly source relatively simple. Further, the vibrations associated with normal speech are readily transmitted through air, and are thus available for an unfriendly eavesdropper to hear. Further, any audible sound or vibration present in a fluid medium (whether air or water) may comprise distracting background noise that needs to be eliminated before a desired operation can be carried out. Thus, there is also a need in the art for systems that reduce or cancel vibrations in a fluid medium as well as in a solid medium.
Unfortunately, effectively eliminating or reducing vibrations in a solid medium presents a formidable task. While sometimes "shock absorbers", or equivalent devices, may be used to isolate a source of vibrations from a medium remote from the source, such devices are rarely effective at reducing or eliminating vibrations within a given medium when the source of the vibrations is also within the medium.
In order to reduce vibrations that cannot be eliminated through absorber-type isolation devices, it is known in the art to set up counter-vibrations using a suitable vibration source for the purpose of canceling the unwanted vibrations at a desired target point within the medium. Unfortunately, predicting the type and amplitude of the counter-vibrations that must be applied at a given point of the medium in order to effectively cancel the unwanted vibrations at a desired target point within the medium poses an extremely complex problem that is not easily solved. Moreover, the difficulty of this problem is significantly compounded when the problem must be solved in real time. Further, the complexity of the problem expands enormously if either the target point moves or if the character and nature of the unwanted vibration (source vibration) changes.
The vibration cancellation problem becomes virtually impossible to solve using classical techniques when there is more than one desired target point in the same medium that is to be quieted. Further, when a fluid medium is involved, the problem becomes even more difficult due to the non-rigid dynamics of the fluid medium itself. What is needed, therefore, is a vibration reduction system that readily reduces vibrations in real time at one or more target locations in a desired medium, regardless of whether the medium is rigid or fluid, and regardless of the types of vibrations that may be present at the target point(s), and regardless of the location within the medium of the desired target point(s).
Moreover, for some applications, there is a need for a vibration generation system, e.g., a system that generates a desired vibration at the target point that has specified characteristics. For example, the output of vibration actuators are often nonlinear, that is, they produce an output that is distorted both in amplitude and frequency as compared to an input. Therefore, there is a need in the art to linearize the actuator output such that it faithfully reproduces the desired input signal. A vibration generation system has wide applicability, for example, in shake tables and fixtures used to subject various objects and structures to a wide variety of forces, and in seismic oil exploration equipment.
The present invention advantageously addresses the above and other needs.